Description (taken directly from the application): Consistent, integrated and high quality morphologic and immunohistologic analyses of tissue samples from the 4 projects will greatly benefit the Program Project. Use of the core will facilitate evaluation of cellular and tissue injury, testing of transgenes, and the effects of interventional strategies, including short term effects on inflammation (e.g. in endotoxemia), as well as in serial studies of islet transplant rejection. This Core will provide immunopathology support for the 4 projects of the program, concentrating on immunohistologic applications. We suggest that the results of such studies will be a prime means to assess the mechanisms of tolerance in allo- and xenogeneic responses, and the effects of agents or strategies used in attempts to circumvent this process. We will focus on the answers to such questions as what leukocytes are present, what are their cytokine products, how do parenchymal cells react, are protective genes induced, and to what extent are functionally relevant molecules associated with the expression of cytokines or other inducing stimuli? The responses to these questions will guide each of the projects and stimulate further experimentation.